Currency pair fundamental analysis
A currency price is a ratio of two economies, so every FX view is two macro views wearing one quote: rate differentials are the fast anchor, purchasing power parity the slow one, and the dollar plays by different rules than everyone else.
A currency price is a ratio of two economies, so every FX view is two macro views wearing one quote. It is the largest market on earth, open around the clock, and the purest expression of macro investing: no earnings calls, no management, just rates, growth, flows and policy on both sides of a pair.
Rate differentials: the fast anchor
Money flows toward yield. When one central bank pays 5% and another 1%, capital migrates to the higher rate, bidding that currency up, which is why FX traders watch central banks the way equity analysts watch earnings. What moves the price is not the level but the change in expectations: a hawkish surprise repriced in seconds, a cutting cycle priced months before it starts. The instrument-grade summary is the two-year government yield spread between the pair's economies, which tracks major pairs remarkably well over months.
The carry trade: harvesting the differential
borrow at 1% (funding currency) -> convert -> deposit at 5% (target) carry = +4% per year, IF the exchange rate holds still uncovered interest parity says the rate difference should be erased by depreciation of the high yielder. Empirically it often is not, for years: the "forward premium puzzle". Carry pays like selling insurance: steady premiums, then a crisis takes years of them back in weeks.
Carry is one of the oldest systematic FX returns, and its risk profile is the textbook example of negative skew: profitable most months, catastrophic occasionally, because when risk appetite breaks, everyone unwinds the same funding currencies at once. The yen carry unwinds of 2008 and 2024 are the canonical case studies.
Purchasing power parity: the slow anchor
In the long run, exchange rates drift toward equalizing what money buys: if a basket costs 30% less in one country, its currency is "cheap" and, over five to ten years, tends to close part of the gap. PPP is useless for timing and excellent for context: it tells you which side of expensive a currency starts from, which conditions how much bad news is already priced. Professionals treat PPP misvaluation as a tailwind gauge, never a trigger.
Balance of payments: the flow accounting
- Current account. A persistent deficit means the country must import capital every day to hold its exchange rate; a surplus country exports capital. Deficits are fine until the financing mood changes, which is the anatomy of most EM currency crises.
- Terms of trade. Commodity exporters' currencies ride their export prices; the Australian dollar tracks iron ore and the Canadian dollar oil closely enough that traders use them as commodity proxies.
- Reserves and intervention. Central banks can lean against moves; watching reserve levels tells you how long they can afford to.
The dollar: not one currency among many
The dollar is the invoicing, funding and reserve currency of the world, which gives it a unique property: it strengthens in global stress even when the stress originates in America, because worldwide dollar debts must be serviced and dollars are hoarded. The "dollar smile": strong when the US booms, strong in global crisis, soft in the mild middle. Every other currency view implicitly contains a dollar view, and a portfolio's dollar exposure is a risk factor whether chosen or not.
How professionals construct FX trades
| Choice | The professional habit |
|---|---|
| The pair | Express the view against the cleanest counterpart, not reflexively the dollar: bullish Japan hawkishness is short EUR/JPY if Europe is the laggard |
| The instrument | Forwards for funds (carry is embedded in the forward points); options where the thesis is an event with a date |
| The stop discipline | FX trends persist but gap on policy; sizing assumes the overnight gap, not the average day |
| The crowding check | CFTC positioning and risk-reversal skew: when everyone is short a currency, the squeeze is the risk |
Every international portfolio is an FX portfolio whether it wants to be or not. An unhedged foreign equity position is equity risk PLUS currency risk; hedging costs roughly the rate differential. The professional default: hedge where the currency is not part of the thesis, and size the currency separately where it is. Letting residual FX exposure ride unexamined is a position no one chose.
- Currency pair
- FX prices are ratios: EUR/USD is euros priced in dollars. Every position is long one economy's money and short another's, so every FX view is two macro views.
- Rate differential
- The gap between two economies' interest rates, the fast anchor of exchange rates. The two-year government yield spread tracks major pairs remarkably well over months.
- Carry trade
- Borrow the low-rate currency, deposit in the high-rate one, harvest the differential. Pays steadily until a risk shock unwinds everyone at once; the yen unwinds of 2008 and 2024 are the case studies.
- Uncovered interest parity
- The theory that rate differentials should be erased by currency depreciation. Empirically it fails for years at a time (the forward premium puzzle), which is why carry exists as a strategy.
- Negative skew
- A return profile of many small gains and rare large losses, the shape of selling insurance. Carry trades and option selling share it; averages flatter it, and sizing must respect the tail rather than the average.
- Purchasing power parity
- The long-run tendency of exchange rates toward equalizing what money buys across borders. Useless for timing, excellent for knowing which side of expensive a currency starts from.
- Current account
- A country's net trade and income with the world. Persistent deficits must be financed by daily capital imports, which is fine until the financing mood changes: the anatomy of most currency crises.
- Terms of trade
- Export prices over import prices. Commodity exporters' currencies ride their commodities closely enough that traders use the currencies as proxies.
- Dollar smile
- The dollar strengthens when the US booms AND in global crisis (dollar debts must be serviced; dollars get hoarded), softening only in the mild middle. Every portfolio has a dollar exposure whether chosen or not.
- Forward points
- The difference between a currency's forward and spot price, set by the rate differential. Hedging a currency costs roughly its points, which is why hedging high-yielders is expensive.
- Risk reversal
- The implied-volatility gap between out-of-the-money calls and puts on a currency: the options market's directional fear gauge, and a crowding check before entering.
- Currency hedging
- Removing FX risk from an international position, usually with forwards. The professional default: hedge where the currency is not the thesis, size it separately where it is.